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Fish and Consciousness

By Timothy Cocks Philosophy of pain 24 Dec 2015
In the current issue of Animal Sentience: An interdisciplinary Journal on Animal Feeling (stay with me now), Professor Brian Key, Head of the Brain Growth and Regeneration Lab at the University of Queensland, has penned a strongly positioned paper on the topic of whether fish feel pain, titled Why fish do not feel pain  (hang in there, it’s worth it).

Professor Key’s arguments comes down to a number of key points:

Only humans can report feeling pain. In contrast, pain in animals is typically inferred on the basis of nonverbal behaviour

There is compelling evidence that pain in humans is generated by neural activity in the cerebral cortex, in particular a “dynamic core” consisting of somatosensory areas I and II, prefrontal cortex, anterior cingulate cortex and the insular cortex.

According to bioengineering principles, the function of brain regions is determined by their structure, and the specific structure and integration of the cortical regions in the “dynamic core” are necessary for the function of feeling pain

Fish lack the above mentioned neural architecture for feeling pain

Therefore fish do not feel pain

It all seems fairly logical…

But, in order to accept his conclusion, one must accept the veracity of Professor Key’s premises, and this is where the plot thickens. Because, the journal of Animal Sentience uses the fantastic structure of inviting and publishing expert commentaries on Key’s target paper, along with replies from the original author on the commentaries (all of it fully open access to boot). What ensues is a rigorous academic back and forth that is as much about profound questions of human pain and consciousness, as it is about whether a salmon can feel a pulled hypaxial muscle.

At the heart of Professor Key’s argument is a proposition about how humans experience pain, and his paper provides an easily digestible summary of his position regarding the brain structure and function that is responsible for the conscious experience of pain. However it is this key proposition that is most targeted for debate in the commentaries. Amongst the commentators are some real luminaries in the domains of neuroscience, cognitive neuroscience and philosophy of mind, here’s just a sampling:

Riccardo Manzotti – No evidence that pain is painful neural process

“I counterargue that no conclusive evidence supports the sufficiency of any mammalian neural structure to produce pain. We cannot move from contingent necessity in mammals to necessity in every organism.”

Antonio Damasio – Pain and other feelings in animal 

“Evidence from neuroanatomy, neurophysiology, and neuropsychology suggests that the experience of feelings in humans does not depend exclusively on structures of the cerebral cortex. It does not seem warranted to deny the possibility of feeling in animals on the grounds that their cerebral cortices are not comparable to those of humans.”

Marshall Devor – Where is pain in the brain?

“Imaging indeed shows that pain-relevant signals reach the cortex, but not that they underlie the subjective experience of pain. Lesions and stimulation data are more to the point, but Key paints an idiosyncratic and misleading picture of their effects. S1 and S2 ablation does not eliminate evoked or spontaneous pain, although there may be up- or down-modulation…Overall, the case for the cerebral cortex being an essential substrate for pain experience in humans is too equivocal a starting point for ruling out the possibility of pain experience in fish.”

Anil Seth – Why fish pain cannot and should not be ruled out

“[Key’s] strategy fails in three ways. First, non-mammalian consciousness — if it exists — may depend on different mechanisms. Second, accumulating neurophysiological and behavioural evidence, evolutionary considerations, and emerging Bayesian brain theories suggest that if fish can feel at all, they can feel pain. Finally, the qualitative nature of pain and suffering obliges us, via the precautionary principle, to accommodate the possibility of its existence where doubt remains.”

Jaak Panksepp – Brain processes for “good” and “bad” feelings: How far back in evolution.

“I was a bit chagrined that Key spent so much time denying that any form of consciousness can exist below the cortex. Obviously it can…”

Of the 34 commentaries published, only three support Professor Key’s position. But, as Key points out in one of his replies, “science does not prevail by popular opinion. History is plagued with numerous (and often widely accepted) examples of biological phenomena being explained by mysterious forces.” However, Key’s rejoinder in this case seems a little disingenuous, and at risk of sneaking in a straw man. None of the commentaries resort to an appeal to mysterious forces, rather, they focus on Key’s narrow necessity and sufficiency conditions for consciousness experiences of pain, that is – the mammalian cortex. Devor, Damasio and Panksepp all challenge this idea and do so without resorting to “opinion” – they each provide supporting evidence, while also questioning Key’s use and interpretation of empirical evidence offered to support his claims.

For me, the really juicy stuff comes in the commentaries from Anil Seth and Riccardo Manzotti. Seth, cognitive and computational neuroscientist and Editor-in-chief of the just-launched, open access journal Neuroscience of Consciousness, points out that “the biophysical substrates of conscious states (including pain and suffering) in any species, including humans, cannot yet be confidently identified“. More simply put, Seth is arguing that, despite Key’s confidence that conscious experience arises in/from the cortex, we really don’t understand (some would argue we don’t even have the beginning of an idea) how the human brain, or any brains, gives rise to conscious experience. Seth has suggested that the question of how the brain generates conscious experience (begging an obvious question…) is the “most interesting problem in science”. Along with interesting, it may also be one of the most intractable problems in science, and it highlights that despite much progress in understanding pain, we still have no idea how all the carry on in certain nerve fibres and the brain might give rise to ‘hurt’.

Manzotti, professor of psychology at IULM University (Milan) and a proponent of a more radical position on consciousness, points out that “there is no definitive proof that neural activity is sufficient to generate pain. In all known cases, neural structures are involved, but so are bodies, the environment, stimuli, tissue damage, past and future behavior, and social interactions. We have no reason to discard all of that in favor of the neural underpinnings alone.” Manzotti rejects not only Key’s idea that the cortex gives rise to the conscious experience of pain, but rejects the notion that even the entire brain can produce consciousness. Although this idea can sound a bit out-there, Manzotti is certainly not alone in this view, with philosophers of mind such as Alva Noë, Kevin O’Regan, and Evan Thompson (to name just a few that have made past appearances here on NOIjam), and others in the Embodied Cognition and Extended Mind camps arguing, in various flavours, that consciousness experience can not, and does not arise solely from the brain.

If you’ve stuck it out thus far, I hope you can see that the question of whether Nemo feels any pain is, in many ways, really just a subset of the much bigger, and deeper question of how it is that humans experience pain – or consciously experience anything at all. This makes the entire series of Key’s target paper and subsequent commentaries a rich (open access) trove of profound questions and ideas about brains, human pain and conscious experience. I think you’ll enjoy reading many of the papers – and what a great time of year to get comfortable, grab something nice to drink and enjoy some thought provoking, erudite and weighty philosophy of mind reading – that is, if you’re into this kind of thing.

Thoughts, comments and questions, as always, welcome below.


-Tim Cocks

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  1. Thank you Tim. Of course I can’t resist this one:
    Zhuangzi and Huizi were crossing the Hao River by the dam.
    Zhuangzi said, “See how free the fishes leap and dart: that is their happiness.”
    Huizi replied, “Since you are not a fish, how do you know what makes fishes happy?”
    Zhuangzi said, “Since you are not I, how can you possibly know that I do not know what makes fishes happy?”
    Huizi argued, “If I, not being you, cannot know what you know, it follows that you, not being a fish, cannot know what they know. The argument is complete!”
    Zhuangzi said, “Wait a minute! Let us get back to the original question. What you asked me was ‘How do you know what makes fishes happy?’ From the terms of your question, you evidently know I know what makes fishes happy.
    “I know the joy of fishes in the river through my own joy, as I go walking along the same river.”
    Based on translation by Thomas Merton, The Way of Zhuang Tzu, New Directions Books, 1965

    1. Such an awesome little passage Til, and very fitting. It says it all in a very precise way – very Taoist.

      Does anyone reading know what Huizi failed to realize? What does Zhuangzi mean by “walking along the same river”? And how is this relevant to discussions about pain (or happiness for that matter)?

  2. Lovely Tim, just lovely…….if pain is a result of the brain weighing up the World of Sims & DIMs, a biopsychosocial experience then anything that can experience the world can suffer. When Millie was beaten up badly by the neighbourhood bully she definetly behaved as if she was in pain. When I left her behind yesterday as I was going away she hid behind the sofa, obviously very aware that she was being abandoned.! One a more physical and one a very emotional experience! So I believe Nemo, Rudolf, Bambi & Millie can feel pain, don’t you ?
    Millie is my cat by the way 🙂
    On location 🎅🎅🎅

  3. Whether or not fish feel pain is technically a non-issue. The pertinent issue is suffering. Suffering requires self-awareness. Since fish have no self, they cannot possibly suffer. Suffering requires a subject – a ‘sufferer’. No such thing in fish.

    It makes perfect sense that all living creatures will react to pain. How well would a species survive if it didn’t care about being eaten by a predator? Being eaten will end your species very quickly! I couldn’t for a moment conceieve of fish not feeling and reacting to pain. But once again, it’s a non issue unless there’s a ‘little me’ inside the fish screaming “ouch! stop that!”. And there isn’t.

    It’s quite a feat of psychological projection to imagine that just because a fish bleeds red blood, has two eyes and reacts to pain, that it must therefore have a self which suffers. You could stab a fish with a spear and the amount of suffering will be equal to a tree which has been hit by lightning. Zero.

    \\\\\\ Consciousness and ‘self’ are not synonymous. ///////

    Consciousness can exist without self-referencing (as it does in a fish). No self, no suffering, no problem.


  4. The most poignant evidence that self causes suffering, and that pain is very much a secondary issue, is seen in the condition of xenomelia.

    Xenomeliacs perceive part of their body (usually an arm or leg) as not-self. They have been known to severely mutilate the affected body part in all manner of ways, including wrapping the limb in dry ice. Can you imagine the degree of nociceptor firing that would create? And yet the sufferer’s overwhelming emotion is relief. Self is the elephant in the room. Pain is the great distraction. Self matters.

    PS. Huizi failed to realize his essential nature. He failed to realize that what he calls ‘me’ is a fleeting thought. This is the cause of his confusion in the parable, and the cause of his suffering. We all suffer in the same way. Our confusion comes through our struggle to understand suffering through a scientific lens. Science is a magnificent tool, but it can only take us so far.

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